Dynamical ejections of stars due to an accelerating gas filament

• Published in: Monthly notices of the Royal Astronomical Society Vol. 471; no. 3; pp. 3590 - 3598
• Main Authors: Boekholt, T. C. N., Stutz, A. M., Fellhauer, M., Schleicher, D. R. G., Matus Carrillo, D. R.
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.11.2017
• Subjects: ISM: individual objects (Orion A); stars: kinematics and dynamics
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stx1821

Abstract Observations of the Orion A integral shaped filament (ISF) have shown indications of an oscillatory motion of the gas filament. This evidence is based on both the wave-like morphology of the filament and the kinematics of the gas and stars, where the characteristic velocities of the stars require a dynamical heating mechanism. As proposed by Stutz & Gould, such a heating mechanism (the ‘Slingshot’) may be the result of an oscillating gas filament in a gas-dominated (as opposed to stellar-mass dominated) system. Here we test this hypothesis with the first stellar-dynamical simulations in which the stars are subjected to the influence of an oscillating cylindrical potential. The accelerating, cylindrical background potential is populated with a narrow distribution of stars. By coupling the potential to N-body dynamics, we are able to measure the influence of the potential on the stellar distribution. The simulations provide evidence that the slingshot mechanism can successfully reproduce several stringent observational constraints. These include the stellar spread (both in projected position and in velocity) around the filament, the symmetry in these distributions, and a bulk motion of the stars with respect to the filament. Using simple considerations, we show that star–star interactions are incapable of reproducing these spreads on their own when properly accounting for the gas potential. Thus, properly accounting for the gas potential is essential for understanding the dynamical evolution of star-forming filamentary systems in the era of Gaia (Gaia Collaboration 2016).